#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
int main()
{
    int fd;
    char scullo_str[] = {"good morning scullo driver."};
    char read_str[80]={0};
    int ret;

    fd = open("/dev/scull0", O_RDWR);
    if (fd < 0) {
        printf("it is fail to open.\n");
        return -1;
    }
    ret = ioctl(fd, 0);
    if (ret < 0) {
        printf("it is fail to ioctl.\n");
        close(fd);
        return -1;
    }
    close(fd);

    return 0;
}